We've recently released a feature called "Challenges" but it's very much in beta and needs some UX love. We're considering rolling it back until we fix a few issues, so please don't use it too much in the meantime. But if you've tried it, do give us feedback!

Challenges directly affect matchmaking, since it's based on number of games played, and everything seems to indicate challenges increase that number.

If that's the case, it means the more you are challenged, the even longer it takes to get results back from a submission. Given how it's already much slower to get submission results, not to mention increasing the workload of workers, I think it needs to be fixed/removed ASAP.